Method of making nitric acid.



noqsagoas. I Patentefi Aug. 20,- I90I;

C. UEBEL.

7 METHOD OF MAKING NITRIC ACID.

(Application filed Mar. 5, 1801.) (No Model.) 2 Silesia-Shoat l.

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I Patented Aug. 20, I90I. UEBEL.

METHO MAKING NITRIC ACID.

A lication and Mar. 5, 1901.)

Nb. 158L085.

um Model.)

i t UNITED STATES ATEN rat on.

CARL UEBEL, OE AACHEN, GERMANY, ASSIGNOR TO CHEMISCHE FABRIK RHENANIA, OF SAME PLACE.

METHOD OF MAKING NITRIC ACID.

' SPECIFICATION forming part of Letters Patent No. 681,085, dated August 20, 1901.. 1 Applioation filed March 5, 1901. Serial No. 49,966. (No specimens.)

T ctZZ whom it may concern:

lecting the distillate.

i l dated March 10, 1900,)of which the following Io j Nitric acid is generally made by heating a is a specification.

nitrate with sulfuric acid in a retort and col- The temperature of the mixture is slowly raised to 300 oentigrade, and when the nitric acid has all been distilled the fire is drawn, the hot bisulfate is run out of the retort, and the latter is allowed to cool period there is much frothing, so that the retort must be cautiously heated. In the process as commonly conducted, therefore, a continuous manufacture of nitric acid is very difficult.

The present invention relates to a process for the continuous manufacture of nitric acid in which concentrated acid and dilute acid are distilled from the same charge, but in different retorts. In this manner the change of receivers necessary when the whole distillation is conducted in one retort and concentrated acid is required is avoided, and at the same time there is a considerable saving of fuel.

first, that the distillation of concentrated acid subsequent distillation of the dilute acid,

and, second, that the distillation of the dilute acid can be hastened and accomplished without the usual frothing if the charge remaining after the concentrated acid hasbeen distilled is run into hot bisulfate.

The process consists, therefore, in charging nitrate and sulfuric acid or polysulfate into two or more retorts worked successively and distilling concentrated nitric acid therefrom.

Whenthis stage of the operation is complete, the residual charge is transferred to another retort common to all the first-mentioned retorts and containing hot bisulfate, by means of which the dilute nitric acid is distilled. The number of first-named retorts which can be served by one retort containing bisulfate depends, of course, on the relative size of the latter. For the sake of example the process will be described with reference to only three retorts and to an advantageous installation. The latter is shown in the accompanying drawings, in WlllCl1- Figure 1 is a vertical longitudinal section on line A B of Fig. 2, which is a section on line 0 D of Fig. 1. Fig. 3 is a plan, and Fig. 4 is a back view.

A A are the retorts for distilling the concentrated acid provided with charging-openings H H and pipes D D for escape of acidvapor. As the temperature they require is comparatively low-namely, about 170 to 180 centigrade-they are set in branch fines of a furnace F, in the main flue of which is set the bisulfate-retort B, which is heated to about 300 centigrade. By settingretorts A A above retort B the residual charge can be run by gravity from either of the upper retorts into the lower one through a pipe N, con trolled by a valve 1; v. The temperature of the upperlretorts is controlled by dampers z 2, respectively.

E E are pipes providing for escape of vapor from the lower retort B, and o is a valve for withdrawing the molten bisulfate.

The process is conducted in this apparatus as follows: The firehaving been lighted,one of the upper retortssay A-receives through opening Ha charge of saltpeter and sulfuric acid or fused'polysulfate. The damper z is now opened and the retort heated until the desired proportion of the nitric acid has distilled over. The contents of A are now allowed to flow slowly through valve 1) into the lower retort B, which always contains a quan- Ioo while the second upper retort A is being charged and heated, so that there is another charge ready for B when its first one has been worked 01f. These operations are repeated to obtain a constant distillation of acid.

I am aware that it has been proposed to distil nitric acid by charging nitrate into hot polysulfate; -but a continuous distillation of acid is not possible by this process, and I make no claim thereto.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

A process of making nitric acid, consisting inpartly decomposing a nitrate and sulfuric acid at a suitable temperature, and then subjecting the partly-decomposed mixture to bisulfate of a greater temperature than that employed for thefirst reaction.

In testimony whereof I have hereunto set my hand in presence of two subscribing Wit- 

